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Abstract:

Methods and apparatus for voice domain operation are described herein.
One example method includes determining that an LTE network is not
preferred for voice service provision; storing an identification of the
LTE network that is not preferred for voice service provision; and
accessing the stored identification of the LTE network that is not
preferred for voice service provision.

Claims:

1. A method comprising: determining that an LTE network is not preferred
for voice service provision; storing an identification of the LTE network
that is not preferred for voice service provision; and accessing the
stored identification of the LTE network that is not preferred for voice
service provision.

2. The method of claim 1, wherein determining that the LTE network is not
preferred for voice service provision comprises determining that voice
service is unavailable from the LTE network.

3. The method of claim 1, wherein determining that the LTE network is not
preferred for voice service provision comprises determining that voice
service from the LTE network is less preferred than voice service from
another network.

4. The method of claim 1, wherein determining that the LTE network is not
preferred for voice service provision comprises receiving a reject cause
from the LTE network.

5. The method of claim 4, wherein the reject cause comprises a rejection
indicating that circuit switched domain services are available when a
mobile station in an S1 mode having a voice domain preference of circuit
switched voice only requests registration for circuits switched services.

6. The method of claim 1, wherein determining that the LTE network is not
preferred for voice service provision comprises receiving an indication
from an LTE network that voice is not supported.

7-9. (canceled)

10. The method of claim 1, further including determining that a mobile
station is in a voice centric mode of operation.

12. The method of claim 1, wherein storing the identification of the LTE
network comprises storing a tracking area identifier (TAI) of the LTE
network that is not preferred for voice service provision.

13. The method of claim 1, wherein storing the identification of the LTE
network comprises storing a public land mobile network (PLMN) identifier
of the LTE network that is not preferred for voice service provision.

14. The method of claim 1, wherein storing the identification of the LTE
network comprises storing a time stamp associated with the identification
of the LTE network.

15. The method of claim 1, wherein storing the identification of the LTE
network comprises storage within user equipment (UE).

16. (canceled)

17. The method of claim 1, further comprising reselecting to a different
radio access technology.

18. The method of claim 17, wherein reselecting to a different radio
access technology comprises not reselecting to any LTE network previously
identified as not preferred for voice service provision.

19. (canceled)

20. The method of claim 1, wherein storing the identification of the LTE
network that is not preferred for voice service provision comprises
adding the identification to a list of identifiers indicating networks
that are not preferred for voice service provision.

21. (canceled)

22. The method of claim 20, further comprising reselecting to a different
radio access technology, wherein reselecting to the different radio
access technology comprises not reselecting to any LTE network identified
in the list of identifiers indicating networks that are not preferred for
voice service provision.

23. The method of claim 20 further comprising selecting a public land
mobile network (PLMN) that is not identified in the list of identifiers.

24. (canceled)

25. The method of claim 20 further comprising selecting a cell that is
not identified in the list of identifiers.

26. The method of claim 25, wherein the list of identifiers comprises
tracking area identifiers.

27. The method of claim 20 further comprising reselecting a cell that is
not identified in the list of identifiers.

28-62. (canceled)

Description:

FIELD OF THE DISCLOSURE

[0001] This disclosure relates generally to mobile communications and,
more particularly, to methods and apparatus for voice domain operation.

BACKGROUND

[0002] User equipment (UE) operating in a voice-centric operating mode
will connect to network facilities to provide voice services. For
example, UE may attempt to connect to long term evolution (LTE) network
coverage to obtain voice services and, if voice services are unavailable,
may reselect to second or third generation (2G/3G) network coverage.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003]FIG. 1 is a block diagram of a communication network in which UE
may operate.

[0005]FIG. 3 is a block diagram of functionality that may be implemented
in the UE of FIG. 2.

[0006]FIG. 4 is a flowchart of an example process that may be carried out
by a voice-centric UE.

[0007]FIG. 5 is a flowchart of an example scan process that may be
carried out by a voice-centric UE.

[0008]FIG. 6 is a flowchart of an example list maintenance process that
may be carried out by a voice-centric UE.

[0009] FIG. 7 is a block diagram of an example processing system capable
of implementing the apparatus and methods disclosed herein.

DETAILED DESCRIPTION

[0010] The methods and apparatus herein are described in conjunction with
various UE usage settings, which are also referred to as home public land
mobile network (HPLMN) operator preferences. The UE usage settings are
provided to the UE by the network operator to specify how a UE that is
both circuit-switched fallback (CSFB) capable and internet multimedia
subsystem (IMS) capable is supposed to handle voice services. Example
usage settings are described below.

[0011] In the circuit-switched (CS) voice only usage setting, the UE will
use only the CS domain (possibly using IMS signaling, per 3GPP TS 23.292)
to originate voice calls and the UE will not attempt to initiate voice
sessions over IMS using a packet switched (PS) bearer.

[0012] In the CS Voice preferred, IMS PS Voice as secondary usage setting,
if CS voice is available the UE will use the CS domain (possibly using
IMS signaling, see 3GPP TS 23.292) to originate and terminate voice
calls. The UE attempts combined evolved packet system/international
mobile subscriber identity (EPS/IMSI) attach or combined tracking
area/location area (TA/LA) Update procedures (as per 3GPP TS 23.272). If
combined EPS/IMSI attach or combined TA/LA Update procedures fail to
register the IMSI in the CS domain or succeed with a small message only
"SMS-only" indication or succeed with a "CSFB Not Preferred" indication,
the UE attempts to use voice over IMS to originate voice calls. If the UE
fails to use IMS for voice e.g. due to "IMS voice over PS session
supported indication" indicates voice is not supported, the UE behaves as
described for "voice centric" or "data centric" according to its setting.

[0013] In the IMS PS Voice preferred, CS Voice as secondary usage setting,
if IMS voice is available the UE will use IMS to originate and terminate
voice sessions. The UE may attempt combined EPS/IMSI attach with or
without "SMS only," combined TA/LA Update with or without "SMS only" or
EPS attach/tracking area update (TAU) procedures. If the UE fails to use
IMS for voice, e.g. due to "IMS voice over PS session supported
indication" indicates voice is not supported (in Attach accept or
subsequent TAU accept), then the UE uses the CS domain (as defined in
3GPP TS 23.272), possibly using IMS signaling (see 3GPP TS 23.292). If
not already performed, the UE attempts combined TA/LA Update procedures.
If the combined TA/LA Update procedures fail to register the IMSI in the
CS domain or succeed with an "SMS-only" indication or succeed with a
"CSFB Not Preferred" indication and the UE has failed to use IMS for
voice, the UE behaves as described for "voice centric" or "data centric"
according to its setting.

[0014] In the IMS PS Voice only usage setting, the UE will use IMS to
originate voice sessions and will not attempt CS Voice. The UE may
attempt combined EPS/IMSI attach with "SMS only," combined TA/LA Update
with "SMS only" or EPS attach/TAU. If the UE fails to use IMS for voice
(e.g. due to "IMS voice over PS session supported indication" indicates
voice is not supported on an evolved UMTS Terrestrial Radio Access
Network (E-UTRAN), the UE behaves as described for "voice-centric" or
"data-centric" according to its setting.

[0015] Methods and apparatus for voice domain operation are described
herein. One example method includes determining that an LTE network
(e.g., E-UTRAN) is not preferred for voice service provision; storing an
identification of the LTE network that is not preferred for voice service
provision; and accessing the stored identification of the LTE network
that is not preferred for voice service provision.

[0016] As described herein, when UE decides that it will not register to a
particular LTE network, the UE stores an indication of that LTE network.
That stored information is later used by the UE when selecting or
reselecting an LTE network to avoid selection of an LTE network that was
previously not desired.

[0017]FIG. 1 is a block diagram of a communication system 100 in which a
UE 102 may operate. The example communication system 100 includes a
several tracking areas TA1-TA7 that each comprises one or more cells (not
shown) to form an LTE network of coverage 103. The tracking areas TA1-TA7
could alternatively be routing areas (RAs) or LAs. The tracking areas
TA1-TA7 are associated with each other by their identification on a
tracking area identity (TAI) list that may be provided to the UE 102 by a
mobility manager or any other network component. As shown in the example
communication system 100, the tracking areas TA1-TA7 on a TAI list may
not support all of the same services. For example, tracking areas TA5 and
TA6 do not support voice over internet multimedia subsystem (VoIMS) while
tracking areas TA1-TA4, and TA7 support VoIMS.

[0018] Additionally, all or parts of some of the tracking areas (e.g.,
TA4, TA5, and TA7) may overlap with different network coverage 104. The
network coverage 104 may be provided by 2G and/or 3G network technology,
such as, for example, Global Systems for Mobile enhanced data rates for
GSM evolution (EDGE) radio access network (GERAN), Universal Mobile
Telecommunications System radio access network (UTRAN), etc.

[0019] When the UE 102 first connects with the LTE coverage 103 (e.g.,
inside tracking area TA5), the UE 102 initiates a registration procedure
to a network the UE 102 has designated as having a high priority. The
registration procedure and be an ATTACH procedure, a tracking area update
(TAU), a combined ATTACH, or a combined TAU. In response to the
registration procedure, the UE 102 receives a response when the LTE
coverage 103 has agreed to initiate a connection with the UE 102. The
response includes an indication of the support capabilities of the
tracking area in which the UE 102 is located (e.g., tracking area TA5).

[0020] Of course, a particular tracking area may not provide all the
services needed or preferred by the UE 102. For example, the UE 102 may
be a voice-centric UE that prefers voice service (e.g., VoIMS). Thus,
when the UE 102 accesses TA5, it discovers that VoIMS is not supported by
TA5 and will find that TA5 is not a preferred network for the provision
of voice services because it cannot provide the services needed by the UE
102. As explained below, the UE 102 will remember that TA5 is not a
preferred network for voice services provision and will use the
remembered information in the future to avoid attempting to establish
communications with TA5 to obtain voice services. For example, 3GPP
documents S2-094238, S2-094147, C1-092354, S2-094179, C1-092353,
C1-092354, and C1-092867 describe example implementations of indications
of VoIMS support that may be provided to the UE 102. Having failed to
obtain the desired services from the LTE coverage 103 via TA5, the UE 102
will fail over to the 2G/3G coverage 104 in an attempt to obtain voice
services.

[0021] If voice services are not available from the 2G/3G coverage 104,
the UE 102 may again attempt to obtain voice services from the LTE
coverage 103, but will recall that TA5 is not preferred for voice
services provision because of the failed prior attempt to obtain voice
services from TA5 and will, therefore, de-prioritize TA5 and may attempt
to obtain voice services from TA7. As shown in the example of FIG. 1, TA7
is capable of providing VoIMS and, therefore, the UE 102 will connect to,
and obtain voice services from, TA7.

[0022] In another example, if the UE 102 attempts to obtain voice services
from LTE coverage 103 and is unable to do so, the UE 102 then tries to
obtain voice services from 2G/3G coverage 104. If the UE 102 is unable to
obtain voice services from 2G/3G coverage 104, the UE 102 may access the
LTE coverage 103 and accept services that do not include voice services.

[0023] Alternatively, as explained below, if the UE 102 obtains voice
services from the 2G/3G coverage 104, the UE 102 may periodically scan
for high priority networks to provide services needed by the UE 102. In
conducting these periodic scans, the UE 102 recalls the TAs that are not
preferred for voice services provision to avoid delays in obtaining
services from a network that can provide the preferred voice service.

[0024]FIG. 2 shows further detail of one example UE 102, which may also
be referred to as a mobile station (MS). The example UE 102 includes a
visual display 212, a keyboard 214, and perhaps one or more auxiliary
user interfaces (UI) 216, each of which is coupled to a controller 206.
The controller 206 includes a connection manager 207 that, as described
in detail below, controls the connections the UE 102 makes with one or
more networks (e.g., LTE networks, 2G/3G networks, etc.). Example methods
and apparatus to implement the connection manager 207 are described in
conjunction with FIGS. 3-6.

[0025] The controller 206 is also coupled to a radio frequency (RF)
transceiver circuitry 208, which is further coupled to an antenna 210. In
one example, the controller 206 is implemented using a central processing
unit (CPU) that runs operating system software stored in a memory 243.
The memory 243 also stores information (e.g., a list) identifying public
land mobile networks (PLMNs) and/or TAs of networks that are
non-preferred for voice service provision, which may be referred to as a
"non-preferred TAs for voice service" list 245. The designation of
"non-preferred" is representative of one network or TA being less
preferable to other networks or TAs through which voice service may be
provisioned. In one example, an LTE network through which voice service
is not available is "non-preferred."

[0026] As explained below, the list 245 stores information that the UE 102
may use to avoid attempting network connections that will not provide
voice services. The controller 206 will normally control overall
operation of UE 102, whereas signal processing operations associated with
communication functions are typically performed by the RF transceiver
circuitry 208. The controller 206 interfaces with the display 212 to
present received information, stored information, user inputs, and the
like.

[0027] The keyboard 214, which may be a telephone type keypad or full
alphanumeric keyboard, is normally provided for entering data for storage
in the UE 102, information for transmission to a network, a telephone
number to place a telephone call, commands to be executed on the UE 102,
and possibly other or different user inputs.

[0029] The UE 102 further includes a battery interface 234 for receiving
one or more rechargeable batteries 232. The battery 232 provides power to
electrical circuitry in UE 102, and the battery interface 234 provides
for a mechanical and electrical connection for the battery 232. The
battery interface 234 is coupled to a regulator 236 that regulates power
V+ to the device. When the UE 102 is operational, an RF transmitter of
the RF transceiver circuitry 208 is typically keyed or turned on only
when it is sending information to the network, and is otherwise turned
off to conserve resources. Similarly, an RF receiver of the RF
transceiver circuitry 208 is typically periodically turned off to
conserve power until it is needed to receive signals or information (if
at all) during designated time periods.

[0030] The UE 102 operates using a Subscriber Identity Module (SIM) 240
that is connected to or inserted in the UE 102 at a SIM interface 242.
Without the SIM 240, the UE 102 may be referred to as mobile equipment
(ME); with the SIM 240, the UE 102 may be referred to as user equipment
(UE). The SIM 240 is one type of a removable memory module or smart card
used to identify an end user of UE 102 (or subscriber) and to personalize
the device, among other things. Without the SIM 240, the example UE 102
is not fully operational for communication through the wireless
communication network 204. By inserting the SIM 240 into the UE 102, an
end user can have access to any and all of his/her subscribed services.

[0031] The SIM 240 generally includes a processor and memory for storing
information. Because the SIM 240 is coupled to the SIM interface 242, it
is coupled to the controller 206 through communication lines 244. To
identify the subscriber, the SIM 240 contains some user parameters such
as an International Mobile Subscriber Identity (IMSI). An advantage of
using the SIM 240 is that end users are not necessarily bound by any
single physical mobile station because the SIM 240 may be used in any
number of different mobile stations. The SIM 240 may store additional
user information for the UE 102 as well, including datebook (or calendar)
information, recent call information, and network connection information.
While the list 245 was shown as being stored in the memory 243, the list
may be stored in the SIM 240, or in any other suitable location.

[0032] The UE 102 may be a single unit, such as a data communication
device, a cellular telephone, a multiple-function communication device
with data (e.g., electronic mail, internet access, personal information
management, etc.) and voice communication capabilities, a personal
digital assistant (PDA) enabled for wireless communication, or a computer
incorporating an internal modem. Alternatively, the UE 102 may be a
multiple-module unit comprising a plurality of separate components,
including but in no way limited to a computer or other device connected
to a wireless modem. In particular, for example, in the mobile station
block diagram of FIG. 2, the RF transceiver circuitry 208 and antenna 210
may be implemented as a radio modem unit that may be inserted into a port
on a laptop computer. In this case, the laptop computer would include the
display 212, keyboard 214, one or more auxiliary UIs 216, and the
controller 206 may be the computer's CPU. It is also contemplated that a
computer or other equipment not normally capable of wireless
communication may be adapted to connect to and effectively assume control
of the RF transceiver circuitry 208 and the antenna 210 of a single-unit
device such as one of those described above.

[0033] The UE 102 communicates in and through the wireless communication
networks, which may be a cellular telecommunications networks. As
described above in conjunction with FIG. 1, the wireless networks may be
configured in accordance with the LTE technology, 2G technology, 3G
technology, or any other suitable technology. The wireless networks may
be configured according to any communication technology including, for
example, universal mobile telecommunications system (UMTS), worldwide
interoperability for microwave access (WiMAX), code division multiple
access (CDMA), General Packet Radio Service (GPRS), Global Systems for
Mobile (GSM), enhanced data rates for GSM evolution (EDGE), GERAN,
evolved UMTS Terrestrial Radio Access Network (E-UTRAN), etc.

[0034] In operation, the UE 102 makes its presence known to wireless
networks by performing what is known as a registration procedure. As
described above, the registration procedure and be an ATTACH procedure, a
tracking area update (TAU), a combined ATTACH, or a combined TAU. This
operation establishes a logical link between the UE 102 and the
network(s) and makes the UE 102 available to receive, for example, pages
via the networks, notifications of incoming data, SMS messages, etc. In
order to send and receive data, the UE 102 assists in activating a packet
data address that it wants to use. This operation makes the UE 102 known
to a packet gateway within the core network; interworking with external
data networks can thereafter commence. User data may be transferred
transparently between the UE 102 and the external data networks using,
for example, encapsulation and tunneling.

[0035] Block diagrams of apparatus and flowcharts representative of
example processes that may be executed to implement some or all of the
elements of the UE 102 are shown in FIGS. 3-6. In the following
description, determining may be any type of process for identifying a
particular result and is not limited to a computational or analysis
process. For example, determining may involve reading an indicator, flag,
register, variable, identifier, etc. to determine whether a service is
supported. In another example, determining may involve querying,
extracting, computing, calculating, etc. to determine a result.

[0036] One example of a connection manager 207 that is shown in FIG. 3
includes a connectivity selector 302, a service availability determiner
304, and a list maintainer 306. FIG. 3 also shows the non-preferred TAs
for voice services list 245, which may or may not form part of the
connection manager 207, but may be used thereby.

[0037] The connectivity selector 302, the service availability determiner
304, and the list maintainer 306 may be implemented in a processor and/or
may be implemented using any desired combination of hardware, firmware,
and/or software. For example, one or more integrated circuits, discrete
semiconductor components, and/or passive electronic components may be
used. Thus, for example, the connectivity selector 302, the service
availability determiner 304, and the list maintainer 306, or parts
thereof, could be implemented using one or more circuit(s), programmable
processor(s), application specific integrated circuit(s) (ASIC(s)),
programmable logic device(s) (PLD(s)), field programmable logic device(s)
(FPLD(s)), etc. The connectivity selector 302, the service availability
determiner 304, and the list maintainer 306, or parts thereof, may be
implemented using instructions, code, and/or other software and/or
firmware, etc. stored on a machine accessible medium and executable by,
for example, a processor (e.g., the example processor 712). When any of
the appended apparatus claims are read to cover a purely software
implementation, at least one of the connectivity selector 302, the
service availability determiner 304, and the list maintainer 306 is
hereby expressly defined to include a tangible medium such as a solid
state memory, a magnetic memory, a DVD, a CD, etc.

[0038] The connectivity selector 302 operates to select a network
connection for the UE 102. For example, the connectivity selector 302 may
read information from, for example, the SIM 240 and the list 245 and uses
this information to select LTE coverage 103, and/or 2G/3G coverage 104.
In one implementation, the SIM 240 may store a priority of networks from
which the UE 102 is to seek connectivity, but the list 245 may store
information indicating that one or more of those networks (e.g., PLMNs or
TAs within those PLMNs) are not preferred for voice service provision.

[0039] The service availability determiner 304 evaluates information from
the connectivity selector 302 to determine whether a necessary, desired,
or preferred service is available from a particular network. For example,
the connectivity selector 302 may attempt to obtain voice services from a
particular LTE network TA (e.g., TA5 of FIG. 1), when voice services are
not available from that particular LTE network TA. The service
availability determiner 304 determines that such services, which were
requested by the connectivity selector 302, are unavailable or not
preferred. Such information is passed to the list maintainer 306.

[0040] The list maintainer 306 adds information to and removes information
from the list 245. For example, when the service availability determiner
304 determines that a particular LTE TA cannot provide voice service, or
that the TA is not preferred for voice service provisioning, the service
availability determiner 304 informs the list maintainer 306 of the same
so that the TAI's of the TAs that are not preferred for voice service
provisioning can be added to the list 245, if the TAI's are not already
stored in the list. In one example, if the TAI of the LTE TA or TAs in
the TAI list that cannot provide voice service is or are already in the
list 245, the previous listing of the TAI is refreshed by adding the TAI
as a new entry in the list 245. For example, the UE 102 may have tried a
first TA (e.g., TA5), which fails and the TAI of which is added to the
list 245, and TAIs of the TAs in the TAI list that a mobility management
entity (MME) returns to the UE 102 in the network registration are added
to the list 245 if not already present. Subsequently, the UE 102 may try
to register with a second TA (e.g., TA7), which is not on the list 245.
In response to the registration from the UE 102, an MME returns a TAI
list that also contains an indication of TA5. In this way, the indication
of TA5 is refreshed in the list 245, and the TAI of each TA contained in
the TAI list is also added to the list 245 if not already present. The
MME can provide different TAI lists when the UE 102 attempts registration
in a first TAx and in a second TAv, even if the TAI list provided by the
MME pursuant to the EU registering to the network in TAx contains TAv, or
when the TAI list provided in TAv contains TAx.

[0041] In this manner, the UE 102 can track networks (e.g., PLMNs) or
network portions (e.g., TAs) with which the UE 102 decided previously not
to register for any service so that this information can be used by the
connectivity selector 302. Using this information, the connectivity
selector 302 can avoid attempting network connections it knows cannot
provision voice services in a preferred manner, thereby saving time and
enhancing the user experience with the UE 102. Thus, the list 245
prevents repeated attempts of an evolved packet system capable
(EPS-capable), voice centric UE 102 to get voice services from TAs from
which the UE 102 previously tried and failed to get voice services.

[0042] The list maintainer 306 may update the list 245 at various
intervals or upon various events or series of events. For example, the
list maintainer 306 may update the list when: (1) the voice-centric UE
102 runs the voice domain selection process as defined in 3GPP TC 23.221
and concludes that voice services are not available in a TA and thus the
UE 102 must disable LTE (e.g., E-UTRAN) capabilities and reselect to
2G/3G (e.g., GERAN/UTRAN) or (2) the UE 102 receives a reject cause #18
(circuit-switched domain available) when the UE 102 attempts to register
for circuit-switched services when in S1 mode and voice domain preference
of the UE 102 is "CS voice only."

[0043] More than one list may be maintained. For example, the list
maintainer 306 of the UE 102 could maintain two or more lists. There may
be one list that identifies non-preferred TAs for IMS Voice over PS,
containing the TAs in which the UE 102 failed to obtain support for voice
over IMS due to PS Voice over IMS not being supported. This list can
nominally be termed "Non-preferred TAs for IMS voice over PS" list. There
may also be another list identifies non-preferred TAs for
circuit-switched fallback (CSFB) service, which contains the TAs in which
the UE 102 failed to obtain CSFB service. This list can nominally be
termed "Non-preferred TAs for CSFB" list. There may also be a list
indicating TAs in which no voice service (e.g., either IMS or CSFB) is
available. This list may be called "TAs with voice not available." Thus,
different types of lists may have different types of specificity, ranging
from specifying voice unavailability to the particular reasons for voice
unavailability. Any desired combination of these lists may be used within
the UE 102. The characteristics, maintenance and usage of these two lists
will follow the principles described herein with respect to the list 245.

[0044] FIGS. 4-6 depict example flow diagrams representative of processes
that may be implemented using, for example, computer readable
instructions. The example processes of FIGS. 4-6 may be performed using
one or more processors (e.g., the processor 712), controllers (e.g., the
controller 206), and/or any other suitable processing devices. For
example, the example processes of FIGS. 4-6 may be implemented using
coded instructions (e.g., computer readable instructions) stored on one
or more tangible computer readable media such as flash memory, read-only
memory (ROM), and/or random-access memory (RAM). As used herein, the term
tangible computer readable medium is expressly defined to include any
type of computer readable storage and to exclude propagating signals.
Additionally or alternatively, the example processes of FIGS. 4-6 may be
implemented using coded instructions (e.g., computer readable
instructions) stored on one or more non-transitory computer readable
media such as flash memory, read-only memory (ROM), random-access memory
(RAM), cache, or any other storage media in which information is stored
for any duration (e.g., for extended time periods, permanently, brief
instances, for temporarily buffering, and/or for caching of the
information). As used herein, the term non-transitory computer readable
medium is expressly defined to include any type of computer readable
medium and to exclude propagating signals.

[0045] Alternatively, some or all of the example processes of FIGS. 4-6
may be implemented using any combination(s) of logic, such as application
specific integrated circuit(s) (ASIC(s)), programmable logic device(s)
(PLD(s)), field programmable logic device(s) (FPLD(s)), discrete logic,
hardware, firmware, etc. Also, some or all of the example processes of
FIGS. 4-6 may be implemented manually or as any combination(s) of any of
the foregoing techniques, for example, any combination of firmware,
software, discrete logic and/or hardware. Further, although the example
processes of FIGS. 4-6 are described with reference to the flow diagrams
of FIGS. 4-6, other methods of implementing the processes of FIGS. 4-6
may be employed. For example, the order of execution of the blocks may be
changed, and/or some of the blocks described may be changed, eliminated,
sub-divided, or combined. Additionally, any or all of the example
processes of FIGS. 4-6 may be performed sequentially and/or in parallel
by, for example, separate processing threads, processors, devices,
discrete logic, circuits, etc.

[0046] A process 400 that may be carried out by a voice-centric UE (e.g.,
the UE 102) is shown in FIG. 4. Although the process of FIG. 4 is
described in connection with the connection manager 207 of FIG. 3, this
is merely one example description and the process of FIG. 4 could be
carried out by any portion of the UE 102, including a connection manager
207 that is not configured as shown in FIG. 3.

[0047] The connectivity selector 302 of the UE 102 selects use of an LTE
network (block 402) and the service availability determiner 304
determines if voice service is available in LTE (block 404). If voice
service is available, the connectivity selector 302 uses the LTE voice
service (block 406).

[0048] However, if the service availability determiner 304 determines that
voice service is not available in LTE (block 404) (i.e., that LTE is not
preferred for voice service provision), the list maintainer 306 adds the
LTE network (e.g., the PLMN ID), or the relevant TAIs of the LTE network
to the list 245 (block 408). Voice service unavailability or a preference
not to provision voice service through LTE may be because VoIMS is not
supported, combined registration for CSFB service failed, the UE 102
failed to register with the internet multimedia control network subsystem
for voice, the UE 102 is voice-centric with IMS Voice not available and
receives a combined attach accept with a circuit-switched fallback not
preferred indication or a short message service only indication.
Additionally or alternatively, the list maintainer 306 may add an
indication of the PLMN (e.g., a PLMN ID, such as MCC+MNC derived from
TAI) to the list 245. The PLMN indicator may also include an indication
as to whether all TAs in the PLMN are indicated as not preferred. The
list maintainer 306 may timestamp the entries it makes in the list 245 so
that later processing may be used to eliminate stale information in the
list 245.

[0049] The service availability determiner 304 having not found the LTE
network as preferable for the provision of voice services (block 404) and
the list maintainer 306 making an indication of the same in the list 245
(block 408), the connectivity selector 302 reselects network connectivity
to 2G/3G coverage 104 (block 410) and disables the LTE communication
capabilities (block 412).

[0050] As long as the connectivity selector 302 determines that a 2G/3G
failure has not occurred (block 414), the UE 102 camps on the 2G/3G
network connectivity 104 (block 416) until it is time for a periodic scan
(block 418). If, however, the connectivity selector 302 determines that a
2G/3G failure has occurred, or a connection to 2G/3G connectivity never
occurred (block 414), the connectivity selector 302 reenables LTE
capabilities and reselects to an LTE network and attempts to obtain voice
service (through the same or different PLMN and/or TA). However, even
though that LTE network may not be a preferred provider of voice services
or may not provide voice services at all (block 420), the UE 102 remains
connected to the LTE network without voice services even though the UE
102 is voice-centric, and operates as such until it is time for a
periodic scan (block 418).

[0051] The decision whether to re-enable the LTE capabilities and/or to
remain connected to the LTE network without voice service can be made
depending on an operator configuration. The operator can provide such
configuration in the UE 102 through, for example, an over-the-air (OTA)
technique or through an open mobile alliance device management (OMA DM)
message, a specific management object, or a downlink message that is
broadcast to a number of UEs or a dedicated transmission to the UE 102.

[0052] When it is time for a scan (block 418), a scan, one example of
which is shown in FIG. 5, is carried out (block 422). The scan may be a
periodic scan or a scan that is triggered by an event (e.g., an
application on the UE 102 and/or a scan triggered by a network. As
explained below, the scan 422 enables the use of LTE capability when
scanning for higher priority PLMNs, in accordance with 3GPP TS 23.122, to
ensure the UE 102 has selected the highest priority PLMN. The ability to
enable LTE capability can be guided by configurable parameters that can
be delivered to the UE 102 by, for example, non-access stratum signaling
(NAS) (e.g., ATTACH ACCEPT, TRACKING AREA UPDATE ACCEPT, ROUTING AREA
UPDATE ACCEPT, SERVICE ACCEPT, or any other NAS signaling), through an
open mobile alliance device management message (OMA DM), or an
over-the-air message, such as an SMS.

[0053] The scan 422 may be carried out by the connectivity selector 302
and may begin by enabling or re-enabling LTE capabilities to facilitate
communication with LTE coverage 103 (block 502). The connectivity
selector 302 then searches for network connectivity according to access
stratum (AS) criteria (block 504) until connectivity meeting the AS
criteria is found (block 506).

[0054] In a first example, when the UE 102 uses the list 245 to perform
PLMN selection, the connectivity selector 302 searches for a PLMN that is
not in the list 245. In a second example, when the UE 102 uses the list
245 to perform cell selection or reselection, the connectivity selector
302 searches for a cell whose TAI is not in the list 245.

[0055] After connectivity meeting the AS criteria is found (block 506),
the connectivity selector 302 determines if any of the connectivity found
is connectivity provided by LTE coverage 103 (block 508). If connectivity
found is from LTE coverage 103 (block 508), the connectivity selector 302
accesses the list 245 to determine if the discovered connectivity is on
the non-preferred list, and disregards the non-preferred candidates for
camping (block 510). By consulting the list 245, the UE 102, which is in
a voice-centric mode, avoids selecting or reselecting to those PLMNs
and/or TAs in the list because the UE 102 has previously determined that
no voice services are provided in, or voice service is not preferably
provisioned by those TAs. As explained above, the UE 102 may store one or
more lists 245. If the UE 102 stores two lists: "TAs with voice
not-available" and "Non-preferred TAs for CSFB," and if the UE 102 is
voice-centric and the UE 102 usage setting are set to "CS only," the UE
102 avoids selecting or reselecting to those PLMNs and/or TAs that are
not in the "TAs with voice not-available" list but that are in the
"Non-preferred TAs for CSFB" list. Operation of the voice domain
selection process specified in 3GPP TS 23.221 determines for a
voice-centric UE whether there is voice service in a candidate TA and
also informs the connectivity selector 302 of the TAs in the TAI list
that cannot provide voice services.

[0056] After the non-preferred LTE candidates are not considered (block
510), or if no LTE coverage is found (block 508), the connectivity
selector 302 opts to camp on candidate connectivity based on criteria
specified by the AS (block 512).

[0057] A list maintenance process 600, which may be carried out by the
list maintainer 306 is shown in FIG. 6. The list maintenance process 600
determines if a list clearing event has occurred (block 602). List
clearing events may include, but are not limited to, user-initiated
requests to clear the list, the UE 102 being powered down, the SIM 240
being removed from the UE 102, the UE 102 usage setting being changed
from voice-centric to data-centric, and/or upon expiration of a timer
against which the list contents are compared, wherein the timer is set by
a user of the UE 102 or the operator providing network services to the UE
102. If a list clearing event has occurred (block 602), the list
maintainer purges 306 the list 245 of some or all entries (block 604).

[0058] If no list clearing event has occurred (block 602), the list
maintainer 306 determines if the list is full (block 606). In one
example, this determination may be made when the list determiner 306 has
information to be stored in the list 245 and there is no additional room
in the list 245. If the list 245 is full, or sufficiently full to merit
deletion of list items, members of the list 245 are deleted from the list
245 according to criteria (block 608). The criteria may include first-in,
first-out, whereby the first, or oldest, entry in the list 245 is removed
first. This may be accomplished by a comparison of timestamps of list
entries.

[0059] FIG. 7 is a block diagram of an example processing system 700
capable of implementing the apparatus and methods disclosed herein. The
processing system 700 can correspond to, for example, a mobile station
processing platform, a network element processing platform, a server, a
personal computer, a personal digital assistant (PDA), an Internet
appliance, a mobile phone, or any other type of computing device. For
example the processing system 700 may implement the mobile station 102
and any component of the mobile communication networks 104.

[0060] The system 700 of the instant example includes a processor 712 such
as a general purpose programmable processor, an embedded processor, a
microcontroller, etc. The processor 712 includes a local memory 714, and
executes coded instructions 716 present in the local memory 714 and/or in
another memory device. The processor 712 may execute, among other things,
machine readable instructions to implement the processes represented in
FIGS. 4-6. The processor 712 may be any type of processing unit, such as
one or more microprocessors from the Intel® Centrino® family of
microprocessors, the Intel® Pentium® family of microprocessors,
the Intel® Itanium® family of microprocessors, and/or the
Intel® XScale® family of processors, one or more microcontrollers
from the ARM® family of microcontrollers, the PICO family of
microcontrollers, etc. Of course, other processors from other families
are also appropriate.

[0061] The processor 712 is in communication with a main memory including
a volatile memory 718 and a non-volatile memory 720 via a bus 722. The
volatile memory 718 may be implemented by Static Random Access Memory
(SRAM), Synchronous Dynamic Random Access Memory (SDRAM), Dynamic Random
Access Memory (DRAM), RAMBUS Dynamic Random Access Memory (RDRAM) and/or
any other type of random access memory device. The non-volatile memory
720 may be implemented by flash memory and/or any other desired type of
memory device. Access to the main memory 718, 720 is typically controlled
by a memory controller (not shown).

[0062] The computer 700 also includes an interface circuit 724. The
interface circuit 724 may be implemented by any type of interface
standard, such as an Ethernet interface, a universal serial bus (USB),
and/or a third generation input/output (3GIO) interface.

[0063] One or more input devices 726 are connected to the interface
circuit 724. The input device(s) 726 permit a user to enter data and
commands into the processor 712. The input device(s) can be implemented
by, for example, a keyboard, a mouse, a touchscreen, a track-pad, a
trackball, an isopoint and/or a voice recognition system.

[0064] One or more output devices 728 are also connected to the interface
circuit 724. The output devices 728 can be implemented, for example, by
display devices (e.g., a liquid crystal display), by a printer and/or by
speakers. The interface circuit 724, thus, typically includes a graphics
driver card.

[0065] The interface circuit 724 also includes a communication device such
as a modem or network interface card to facilitate exchange of data with
external computers via a network (e.g., an Ethernet connection, a digital
subscriber line (DSL), a telephone line, coaxial cable, a cellular
telephone system such as an EGPRS-compliant system, etc.).

[0066] In some examples, the computer 700 also includes one or more mass
storage devices 730 for storing software and data. Examples of such mass
storage devices 730 include floppy disk drives, hard drive disks, compact
disk drives and digital versatile disk (DVD) drives.

[0067] As an alternative to implementing the methods and/or apparatus
described herein in a system such as the device of FIG. 7, the methods
and or apparatus described herein may be embedded in a structure such as
a processor and/or an ASIC (application specific integrated circuit).

[0068] As noted above, the foregoing may be implemented in any number of
different ways. One of these ways is through a standards-based approach.
To that end, the following--illustrate how to facilitate the concepts
described herein in communications standards.

3.7 Non-preferred TAs in E-UTRAN for voice centric MS To prevent repeated
attempts from an EPS capable voice centric MS for getting voice services
in TAs in which the MS had tried and failed to get voice services before,
the MS keeps a list of "non-preferred TAs for voice services". This list
of "non-preferred TAs for voice services" is updated each time the voice
centric MS:-- [0070] runs the voice domain selection process as defined
3GPP TS 23.221 [xx] and concludes that voice services is not available in
a TA and thus the MS must disable E-UTRAN capabilities and reselect to
GERAN/UTRAN; or [0071] the MS receives reject cause #18 (CS domain
available) when MS attempts to register for CS services when in S1-mode
and voice domain preference of the MS is "CS voice only". In these cases,
the MS shall store, if not already in the list, the corresponding TAI,
plus each TAI in the TAI list if available to the MS, into the
"non-preferred TAs for voice services" list. The maximum number of
possible entries in this list is implementation dependent but there must
be space for at least one entry. This list, if existing, is deleted
when:-- [0072] the MS is switched off; [0073] the SIM is removed; [0074]
the MS usage setting is changed from voice centric to data centric; or
[0075] an implementation dependent timer expires. When this list of
"non-preferred TAs for voice services" is full and more entries have to
be stored, the oldest entries are deleted. The contents of the
"non-preferred TAs for voice services" list are not considered for the
PLMN selection process of subclause 4.4 of this document. The contents of
the "non-preferred TAs for voice services" list are considered for the
cell selection and cell reselection processes described in 3GPP TS
25.304[32] and 3GPP TS 36.304[43]. 4.9 Avoiding tracking areas in E-UTRAN
that do not support voice services A voice centric MS with entries in
"non-preferred TAs for voice services" list, avoids selecting or
reselcting to those TAs in this list as the MS has determined that no
voice services are provided in those TAs. The running of the voice domain
selection process specified in 3GPP TS 23.221 [xx] determines for a voice
centric MS whether there is or there is not voice services in that TA and
the TAs of the TAI list if that is available to the MS.

[0076] Additionally, 3GPP TS 24.301, version 9.2.0, "Non-Access-Stratum
(NAS) protocol for Evolved Packet System (EPS) Architectural
Requirements" could be augmented to include the changes shown below,
wherein underlined text is added and strikeout text is deleted:

4.5 Disabling and re-enabling of UE's E-UTRA capability When the UE
supporting the A/Gb and/or Iu mode together with the 51 mode needs to
stay in A/Gb or Iu mode, in order to prevent unwanted handover or cell
reselection from UTRAN/GERAN to E-UTRAN, the UE shall disable itsthe
E-UTRA capability and does the following:-- [0077] the UE shall not set
the E-UTRA support bits of the MS Radio Access capability IE (see 3GPP TS
24.008[13], subclause 10.5.5.12a), the E-UTRA support bits of Mobile
Station Classmark 3 IE (see 3GPP TS 24.008[13], subclause 10.5.1.7) and
the ISR support bit of the MS network capability IE (see 3GPP TS
24.008[13], subclause 10.5.5.12) in the ATTACH REQUEST message and the
ROUTING AREA UPDATE REQUEST message after it selects GERAN or UTRAN;
[0078] if the UE supports the "non-preferred TAs for voice services" list
as defined in 3GPP TS 23.122[6], the TAI of the cell in which the UE is
currently in shall be added to the "non-preferred TAs for voice services"
list. If the UE has a valid TAI list received from the network at the
last registration update or GUTI reallocation, then each TAI of that TAI
list shall also be added to the "non-preferred TAs for voice services"
list. The "non-preferred TAs for voice services" list shall then be
provided to lower layer for cell selection and reselection as defined in
3GPP TS 25.304[15A] and 3GPP TS 36.304[21]; and [0079] the UE NAS layer
shall indicate the access stratum layer(s) of disabling of the E-UTRA
capability.

[0080] Methods and apparatus for voice domain operation are described
herein. One example method includes determining that an LTE network is
not preferred for voice service provision; storing an identification of
the LTE network that is not preferred for voice service provision; and
accessing the stored identification of the LTE network that is not
preferred for voice service provision.

[0081] As described herein, when UE decides that it will not register to a
particular LTE network, the UE stores an indication of that LTE network.
That stored information is later used by the UE when selecting or
reselecting an LTE network to avoid selection of an LTE network that was
previously not desired. Another method described herein includes
attempting a connection with a first LTE network to obtain voice service;
determining that the LTE network is not preferred for voice service
provision; determining that voice service is not available from an
alternate network; attempting a connection with a second LTE network to
obtain the preferred voice service; determining that the second LTE
network is not preferred for voice service provision; and connecting with
the second LTE network even though the second LTE network is not
preferred for voice service.

[0082] According to this method, attempting the connection with the first
LTE network includes attempting to connect with a first public land
mobile network and attempting the connection with the second LTE network
includes attempting to connect with a second public land mobile network
different from the first public land mobile network. Connecting with the
second LTE network is an operator-controlled configuration. The
operator-controlled configuration is provided to user equipment using an
over-the-air message, an open mobile alliance device management message,
a specific management object, or a downlink message.

[0083] Determining that the second LTE network is not preferred for voice
service provision comprises receiving a message. The message may be one
or more of an indication that voice over internet multimedia subsystem is
not supported, an indication that a combined registration for circuit
switched fallback service failed, an indication that registration with
the internet multimedia control network for voice failed, an indication
of a combined attached accept with circuit switched services specified as
not preferred, or an indication of a combined attached accept with small
message services only specified. In the foregoing, the first LTE network
is different from the second LTE network.

[0084] Another method includes attempting to connect with an LTE network
to obtain voice service; determining that the LTE network is not
preferred for voice service provision; disabling LTE capabilities;
connecting to an alternate network to obtain voice service; and scanning
for a higher priority network connection, the scanning including enabling
LTE capabilities and scanning one or more LTE networks, while connected
to the alternate network.

[0085] Scanning for the higher priority network connection comprises
periodic scanning. The scanning for the higher priority network
connection, includes enabling LTE capabilities, includes accessing a
configurable parameter in user equipment. The configurable parameter may
be delivered to the user equipment through non-access stratum signaling,
through an open mobile alliance device management message, or an
over-the-air message.

[0086] Finally, although certain example methods, apparatus and articles
of manufacture have been described herein, the scope of coverage of this
disclosure is not limited thereto. On the contrary, this disclosure
covers all methods, apparatus and articles of manufacture fairly falling
within the scope of the appended claims either literally or under the
doctrine of equivalents.

Patent applications by Chen Ho Chin, Deerlijk BE

Patent applications by Richard Charles Burbidge, Hook GB

Patent applications by Stefano Faccin, Hayward, CA US

Patent applications in class Having a plurality of contiguous regions served by respective fixed stations

Patent applications in all subclasses Having a plurality of contiguous regions served by respective fixed stations